Footwear having lighting devices incorporated therein are known. Lighting devices have been incorporated into a variety of footwear including dress shoes, athletic shoes, boots, sandals, etc. Reasons for including lighting devices in footwear include permitting the wearer to see or be seen in reduced light situations, to provide special effects during entertainment events, or as an element of fashion on the part of the wearer.
There are several implementations of footwear incorporating lighting devices. A first simple implementation includes a light source, (e.g. an incandescent bulb, a neon tube, or a light emitting diode ("LED"), a portable power supply such as a battery and a manually operated on-off switch. These elements are connected as an electric circuit and are located in a convenient location in the footwear, such as within the sole and/or heel structure.
A more complex implementation of lighted footwear includes the provision of a switching circuit to switch the light on and off in association with the presence or the absence of the wearer's foot in the shoe or the contact of the wearer's foot with the ground. The above-incorporated patent application is an example of this second implementation.
A third implementation involves the use of a motion switch which is utilized the detect movement of the wearer's foot. The detection of movement causes the light to illuminate. Such a motion switch could involve the use of a "tilt switch," i.e., a mercury switch, to sense the angular position of the shoe with respect to the ground gradient to activate the circuit at a particular attitude.
Shoes incorporating the above-discussed features to increase the visibility of the wearer often have several shortcomings. Shoes which provide for continuous illumination of the lighting device tend to exhaust batteries more quickly than those that are on only intermittently. Shoes which utilize lighting devices that illuminate only when the foot is in contact with the ground or at a certain angular position relative to the ground (i.e. movement detection type devices) are not effective in providing for increased visibility of the wearer for several reasons. In addition, the lighting systems themselves oftentimes do not operate in a reliable manner.
Further, such shoes are typically expensive to manufacture and produce due to the added cost of the lighting system incorporated therein. Finally, such shoes are typically unsuitable for serious athletic activities. This is due to the reduced structural integrity of the shoe caused by the incorporation of the lighting device, as well as an unacceptable increase in the weight of the shoe.
When footwear is provided with a lighting system that lights when the foot contacts the ground, the light is likely to be obscured by material on the ground when the foot is at ground level. For example, if a shoe is designed to illuminate when the wearer's foot contacts the ground, if the wearer is travelling through moderately high grassy conditions, the light will not be visible due to it being obscured by the grass. The higher the light is above the ground when it illuminates, the further away it can be seen. In addition, if the footwear emits visible light only when the shoe contacts the ground, the illumination typically occurs when the lighting device is in an essentially static condition, i.e., it is not moving when the footwear is on the ground. It is known that moving lights are more readily visible to bystanders.
There are two psychophysical phenomena which act to insure that moving lights will be more readily seen than static ones: First, in a static field, a moving object is more easily detected by the eye than a static one. Second, under appropriate lighting conditions, a moving point source of light is perceived, due to the phenomenon of "persistence," by the human eye (and some cameras) as a large, elongated streak of light "painted" on the retina of the eye by the point source, rather than as a small, moving point of light.
Thus, there is a need for a shoe which incorporates an economical and reliable lighting system that illuminates when the wearer's foot is removed from the ground, and which ceases the illumination when the wearer's foot regains contact with the ground. Such footwear would be more readily visible to third parties and would provide the wearer of the shoe with greater visibility when participating in walking, running and other athletic activities. Such a shoe needs to be capable of being manufactured in a cost-efficient and simplified manner, but must be suitable for use in conducting typical athletic activities by not sacrificing performance and weight factors to accommodate the lighting system.